[dsims000]

My first post. I'm really happy that I read the forum. Great and informative. Love it. Learning a lot.

Okay I have a noise coming from the bottom of my 2006 SAAB 9-7x 5.3i. When I decelerate there is a rattle under my car near the middle of the car. I have been to the dealership. They have tacked my heat sheilds. Replaced my converter (under warranty). I was at the dealership for a total of 8 hours over two Saturdays and all they had was "Well it might be the exhaust but we would have to rip it out and put in a new one. Which isn't under warranty"

Can anyone diagnose what is the problem? It comes from the middle to the passenger side of the car. I can only hear the rattle when I ride next to a wall or a house close to the road.

Thanks in advance for the help. I need it! :tiphat

 

[CSDenali]

Are you sure it isn't the DOD kicking in? (8 cylinders to 4) When mine kicks in the noise is most noticeable at lower speeds and near walls. (echo) It quits when I accelerate or when I come to a stop and the torque converter kicks in. It is a light rattle caused by the slack in the timing chain created in 4 cylinder mode.

 

[dsims000]

Yeah that is exactly The situation my car is in. It's rattles how ypu explained. How simple of a fix is that? :dielaugh: take it to a mechanic and it is a simple fix?

 

[Morty]

I am having a similar issue. On deceleration I hear almost like a valve chiming around. Almost like there is a valve in the exhaust losing the pressure and unable to stay open. Not sure if we have any in the exhausts.

This problem is really really starting to irritate me. I hear it daily from passenger side. It makes no sound on idle or if i rev up. But coming down from speed i hear it.

I have an 06 Envoy Denali. Anyone have any ideas?

 

[kawi6stunna]

I have the same issue, or non-issue. I have an 06 Denali, and I am imagininge it being the spark timing retard on deceleration, but can't quite put my finger on it. Timing chain slack sounds legit, but I would think that if that was the case, that it's an indicator to a loose timing chain, which would end up leading to bigger problems. Is this thread dead, or has anyone resolved this for definite yet??

 

[oo7]

rattle from underneath seems to happen after deceleration

I've got an 07 4wd Trailblazer wit about 107k on it, and I just stated noticing a rattle that I hear more when I'm driving past something big. I thought from what I read it could be the heat shields and stopped worrying, but then I realized I never hear it when I'm stopped even if I rev it. Then I read somewhere it could be the rear transfer, but it sounded like they updated that problem before 07. I read somewhere else to get the fluid changed in the transfer case, and that might be it, I never got that done. JiffyLube didn't have the fluid the last few times I asked.

Something I've noticed is that it sounds about the same in the parking deck as it does on the highway which is why the heat shield theory sounded better than something in the drive train. But when I rev it at the red lights, I can't get it to happen.

Any ideas?

:coffee

 

[EnvoyBoy2004]

Should also check the dust shields on the brake assemblies. As far as the transfer case fluid, that needs to be changed every 50K miles (important) and use only GM Autotrac II fluid.

 

[dsolo3999]

I had the same issue with the rattle during Deceleration around 20 mph. This was misdiagnosed by many, myself included, many times. I have a 06 Denali XL 5.3 and the annoying rattle is due to slop in the timing chain in V4 mode on decel. The DOD system is awful. The AFM lifters end up collapsing and causing hell. I just did a DOD delete because of one of the lifters collapsed. Rather than replace them with new AFM lifters I replaced them all with new non AFM lifters, replaced the cam with a non AFM cam and used a Diablo intune i2 tuner to disable the AFM in the pcm. The engine has never ran so good. Smooth idle and no more rattling, no more sluggish shifting and throttle response, no more drone while cruising, no more oil consumption issues, and I'm actually getting better gas mileage than before.

 

[oo7]

still rattling, could it be the resonator?

I got the fluid changed in the transfer case, and I got the rear brakes and rotors replaced, but the noise is still there. I can't get it to happen when I'm in park, but it happens in the parking deck and out on the highway and the sound isn't any different.

Seems to be from the rear but I could be wrong. I parked it with the rear tires on the sidewalk and slid under it and checked the heat shields and exhaust. It all seemed ok to me. I found where the shield on the gas tank was missing a post that a clip goes on and another clip was loose, but I tucked a plastic bottle cap between the shield and the tank, gave it a drive, heard the noise, then parked it and looked up under there quick and the cap was still there.

I saw some posts about the inside of the can in the back of the exhaust rotting and breaking loose and rattling. If its that, I'd be tempted to just live with it.

I'm hoping its not something broken off in the pumpkin ball rattling, but it seems to be functioning fine.

The other thing I've read about is that it could be a bushing on a sway bar or another suspension component. The suspension has always been overly bouncy, but I don't notice the rattling more when I go over speed bumps or rough pavement either.

I just don't want to be left stranded when what ever it is goes completely bad.

:coffee

 

[ricinalberta]

007

The transfer case was past due for change from what I have read and you may want to check into time frame for future changes as it may be as low as 50000

 

[ricinalberta]

oops

EnvoyBoy2004 posted that info --- missed that